With the advance in semiconductor technology, there has been increasing demand for higher storage capacity, faster processing systems, and high speed communication systems. To meet these demands, the semiconductor industry continues to scale down dimension of devices, and also increase packing density of devices on an integrated circuit (IC) to accommodate a larger number of devices on an IC. However, this approach of scaling down and closely packing of devices on ICs has drawbacks. The scaling down of devices to smaller dimensions can introduce short channel effects in the devices due to the short channel lengths (about approximately 100 nm or less) of the scaled down devices. In addition, closely spaced devices may suffer from disturbances such as electron leakage, noise coupling, or electrostatic coupling. These drawbacks can degrade the operating characteristics and performance of the devices over time. Thus, it is desirable to improve performance of devices in such high density ICs.